<html>
<div>

    <img id="verification" src="code/getCode" style="cursor: pointer;" onclick="my()" title="看不清？换一张" />
</div>
<script>
    function my(){
        var ele = document.getElementById("#verification");
        ele.setAttribute("src","code/getCode?random=" + Math.random());
    }
</script>
</html>